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Chapter V Dielectric Study of ……
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It is quite obvious that for methane µ = 0. The molecules of CH3Cl, CH2Cl2
and CHCl3 are asymmetric and their values of µ are equal to 6.2 x 10 -30 Cm,
5.17 x 10 -30 Cm and 3.8 x 10 -30 Cm ,respectively, but the molecule of CCl4 is
symmetric and its µ = 0 [1].
The polarization is some ordering in space of the electrically charged
particles with their displacement in a dielectric under the dipole moment in
the entire volume of the dielectric and in each separate polarizing constituent
(atoms, ions and molecules).
5.3 Polarization of Dielectrics
Linear dielectric show a direct proportionality between the induced
dipole moment , acquired by the molecule during the process of polarization,
and the electric field E acting on the molecule in dielectric material.
= E (5.8)
The proportionality constant () is known as polarizability.
The polarizability reflects the properties of individual molecule of
dielectric material and not of very large volume. Also it is the most important
microscopic electrical parameter of a dielectric material.
There are four different types of polarizations operational, viz,
electronic, ionic, orientational and space charge polarizations [1-2].
(i) Electronic Polarization
The electronic polarization occurs in all atoms or ions, which can be
observed in all dielectrics irrespective of the presence of other types of
polarizations. All materials consist of ions surrounded by electron clouds. As
electrons are very light they have a rapid response to the external field. The
electronic exchange of the number of ions in the crystals gives local
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